The present disclosure relates generally to dishwashers and, more particularly, to techniques for detecting a water fill level in dishwashers. A dishwasher is a mechanical device for cleaning dishes, utensils and other items. Various types of dishwashers are known and are currently available. Spray dishwashers, for example, spray warm water and detergent within a dishwasher cabinet to wash the items arranged in racks. Typically, the spray dishwasher employs one or more rotating spray arms that spray water through holes formed in the arms, a wash reservoir or “sump” where water is collected and a pump to pump the water from the sump to the spray arms.
A number of techniques have been proposed or suggested for reducing energy and water consumption in dishwashers. Existing water conservation techniques, for example, allow dishwashers to use less water while maintaining water velocity and pressure. One aspect of the known water conservation techniques attempt to only fill the dishwashers to an appropriate water fill amount.
Thus, a number of techniques exist for detecting a water fill level in dishwashers. For example, known techniques use timers or water level sensors to control the water fill level. Generally, when the pump motor stops cavitating, there is an appropriate water fill amount in the dishwasher. One technique for monitoring the cavitation utilizes gradients of the current drawn by the pump motor to detect that the water pump has stopped cavitating. While this technique effectively detects an adequate water fill level, it requires a costly increase in the fine balance of the pump motor rotor so that software algorithms can identify current fluctuations due to cavitation. Otherwise, current fluctuations generated from an unbalanced rotor will cause an error in cavitation detection.
A need therefore exists for improved techniques for detecting a water fill level in dishwashers. A further need exists for non-electronic methods and apparatus for controlling a water fill level in dishwashers.